Carcharhinus leucas

The Sardinian shark [1], bull shark, lamia shark or Zambezi shark is a species of carcarriniform elasmobranch of the family Carcharhinidae. It is one of the few sharks that goes up estuaries to reach freshwater. It can measure up to 3.4 m in length.

Common name

Carcharhinus leucas, known in English-speaking countries as "Bull Shark", should not be confused for this reason with Carcharias taurus, known in Spanish as sand tiger shark (also tiger shark or damselfish) and with whom it does not even share taxonomic order. Applying in this case a literal translation of its common name between these languages is a frequent mistake that confuses very different species.

To avoid ambiguity between these species that are not even phylogenetically close (the last common ancestor of these two species existed until 140 million years ago).

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  Upper part of the jaw

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  Lower jaw

Distribution

It can be found upriver in the Amazon in South America as far as the northern Peru. It is also found in the Zambezi (hence it is also called the Zambezi shark) and the Limpopo in Africa, in Lake Cocibolca in Nicaragua, Tortuguero channels in Costa Rica, in Brisbane in Australia and in the Ganges in India. In the Pacific it is found from Baja California to Peru and Taiwan to Australia and New Zealand. In the Atlantic from the Antilles, Colombia and Venezuela to Brazil.

Natural history

It feeds on all kinds of animals, including other sharks. It can be dangerous for humans, because it hunts in places where people usually swim. The ability that this shark has to enter fresh water is thanks to a special gland that they have in their kidneys that allows them to contain salt water in their organism and expel fresh water, which would be fatal for other species of sharks. Fresh water causes the cells of other sharks to burst and subsequently kill them. These sharks can stay in rivers, lagoons and estuaries for about a year or more, which allows them to get closer to humans. A 2012 study revealed that the Sardinian shark is the shark with the highest bite force at about 612 kg of force for an adult.

It is known that this shark in mating seasons is one of the animals with the highest levels of testosterone, even higher than that of a male African elephant and also in heat, which makes it an extremely territorial animal ^{[citation required]}.

The Sardinian shark has a greenish and light brown color on the upper part of its body, ideal for the habitats in which it is found. Sardinian shark mothers give birth in estuaries, where the young grow and develop to be able to reach a larger size and later go out to sea.

Attacks on humans

Recreation of a Carcharhinus leucas compared to an average human being.

The Sardinian shark or Zambesi shark does not have as exaggerated a man-eating reputation as its relative, the great white shark (Carcharodon carcharias), but its ability to enter rivers and shallow waters, where it hunts, make this shark responsible for most attacks on humans. Often gets too close to divers. Attacks are very rare, but in some seas some nets have been put up to indicate how far people can swim. The ISAF counts, between 1580 until today, a total of 100 confirmed attacks of the Sardinian shark on humans.

Sarde shark in the Bahamas

Natural enemies

Humans are the biggest threat to bull sharks. Larger sharks such as the tiger shark and great white shark may attack them, but they usually only target juveniles. [4] Crocodiles can be a threat to bull sharks in rivers. Saltwater crocodiles have been observed preying on bull sharks in rivers and estuaries of northern Australia [56] and a Nile crocodile was reportedly sighted devouring a bull shark in South Africa.

In popular culture

Since 2011, the bull shark appears on the back of the ₡2000 bills from Costa Rica.

In the video game Maneater the shark that the player controls is part of the lamia shark species.